BARRIER STRUCTURE BASED ON MPMDT/XT COPOLYAMIDE WITH A HIGH Tg

ABSTRACT

A barrier structure for the storage and/or transport of fluids, including at least one barrier layer (1) including an MPMDT/XT copolyamide in which: MPMDT is a unit with an amide motif having a molar ratio of between 5 and 50%, particularly between 5 and 45%, preferably between 15 and 45%, more preferably between 20 and 45%, where MPMD is 2-methyl pentamethylene diamine (MPMD) and T is terephthalic acid, XT being a unit with a majority amide motif having a molar ratio of between 50 and 95%, particularly between 55 and 95%, preferably between 55 and 85%, more preferably between 55 and 80%, where X is a C9 to C18, preferably C9, C10, C11 and C12, linear aliphatic diamine, and where T is terephthalic acid, the copolyamide having a melting point of 250° C.&lt;Tf≤300° C. as determined according to the ISO norm 1 1357-3 (2013).

FIELD OF THE INVENTION

The present invention relates to a barrier structure based on anMPMDT/XT copolyamide with a high Tg, said structure being devoid ofreinforcing fibers. This structure can either consist of a single layerof this polyphthalamide or comprise a layer of MPMDT/XT polyphthalamideand at least one layer of another material.

This barrier structure is of use for objects intended for fluid storageand/or transport, such as bottles, tanks, containers, pipes andreceptacles of any type. This structure can also be in the form of filmswith which are made, for example, packagings which require barrierproperties against fluids such as gases. All these objects exhibit goodbarrier properties, that is to say very low permeability to fluids, inparticular motor-vehicle fluids, in particular to fuels.

The invention also relates to the use of an MPMDT/XT copolyamide with ahigh Tg for producing a structure, in particular a multilayer structure,comprising at least one barrier layer comprising said MPMDT/XTcopolyamide.

The invention also relates to the use of these structures and of theseobjects.

Prior Art and Technical Problem

Regardless of the fluid transported or stored in objects such asbottles, tanks, containers, pipes and receptacles of any type, thematerial in direct contact with the fluid must not be permeable to saidfluid, whether the latter is a liquid or a gas.

Thus, in the motor vehicle field, and the transport field in general,the composition of fuels is constantly changing, in particular forecological reasons, which is resulting in the gradual arrival ofbiofuels on the market. These fuels are more aggressive. Consequently,it proves to be essential to improve the quality of the thermoplasticparts in contact with these new fuels, such as pipes for transportinggasoline.

For reasons of safety and environmental preservation, motor vehiclemanufacturers impose on these pipes both mechanical characteristics suchas resistance to bursting and flexibility with a good impact strengthunder cold conditions (−40° C.) and at high temperature (125° C.), andalso a very low permeability to hydrocarbons and to their additives, inparticular alcohols such as methanol and ethanol. These tubes must alsohave good resistance to fuels and to engine lubrication oils.

Application WO 2014/064375 relates to a composition of or for athermoplastic composite material with a matrix made of semicrystallinepolyamide (PA) having a glass transition temperature Tg of at least 90°C. and a melting point Tm of less than or equal to 280° C., and alsomechanical or structural parts based on said material, and to the use ofthe composition of the invention for parts made of composite materialfor applications in the motor vehicle, railroad, marine, road transport,wind power, sport, aeronautical and aerospace, construction, panel andleisure fields.

This composition can be used for the manufacture of mechanical partsinvolved in applications in the motor vehicle field, but no mention ismade in this application of a structure comprising a layer which is abarrier to a fluid, in particular a fuel. Moreover, this compositionalways comprises reinforcing fibers.

EP 1 988 113 describes molding compositions based on a 10T/6Tcopolyamide with:

-   -   40 to 95 mol % of 10T    -   5 to 40% of 6T.

EP 1 988 113 is silent with regard to the barrier properties ofstructures consisting of a layer of these compositions.

EP 1 741 553 describes a multilayer structure comprising two or morelayers comprising at least one layer (a) comprising (A) an aliphaticpolyamide and a layer (b) comprising a semi-aromatic polyamidecomprising at least 60 mol % of aliphatic diamine having from 9 to 13carbon atoms and at least 50 mol % of terephthalic acid, the layer (b)being the inner layer.

EP 1 741 553 is completely silent with regard to the barrier propertiesof such a structure.

EP 1 860 134 describes a resin of semi-aromatic polyamide comprisingdicarboxylic acid units in which from 50 to 100 mol % of thedicarboxylic acid units are aromatic dicarboxylic acid units, anddiamine units in which from 60 to 100% of the diamine units arealiphatic diamine units having from 9 to 13 carbon atoms, saidsemi-aromatic polyamide having an amine chain end/acid chain end ratioof greater than or equal to 6.

EP 1 860 134 exemplifies in particular 9T/9′T (or 8MT/9T) compounds andshows that the alcohol resistance is reduced when said ratio is lessthan 6 and in particular is 4 or less.

International application WO 10/015786 relates to a copolyamide offormula A/10.T, in which:

A is chosen from a moiety obtained from an aminocarboxylic acid, amoiety obtained from a lactam and a moiety corresponding to the formula(Ca diamine).(Cb (cyclo)aliphatic diacid), with a representing thenumber of carbon atoms in the diamine and b representing the number ofcarbon atoms in the diacid, a and b each being between 4 and 36;

characterized in that it has a polydispersity index, noted PDI, of lessthan or equal to 3.5, measured by gel permeation chromatography.

WO 10/015786 is completely silent with regard to the barrier propertiesof such a structure.

WO 2015/159014 describes a process for producing a thermoplasticmaterial comprising at least one step for injection molding or a stepfor processing by extrusion of a composition of polyamides. A very largenumber of polyamides are claimed, and although the polyamide compositioncan be used to produce a single-layer or multilayer structure, mentionis in no way made of the barrier properties of the structure and inparticular comprising the MXDT/XT copolyamide.

Moreover, these polyamides still remain to be improved, in particular interms of crystallinity, of crystallization kinetics with a view toimproving the temperature resistance of the copolyamide, ofprocessability or else of improving their impact strength properties andalso their barrier properties.

Thus, there is a real need to find polyphthalamides which have improvedproperties, in particular in terms of barrier properties.

BRIEF DESCRIPTION OF THE INVENTION

Surprisingly, it is been found that these needs are met with a structurecomprising at least one layer comprising an MPMDT/XT polyamide, inwhich:

“MPMDT” denotes a unit comprising an amide moiety corresponding to thecondensation product of 2-methylpentamethylenediamine and ofterephthalic acid,XT denotes a unit comprising an amide moiety corresponding to thecondensation product of X, which denotes the residues of an aliphatic,arylaliphatic, cycloaliphatic or aromatic amide, and T which denotesterephthalic acid.MPMDT is present in a molar content ranging from 5 to 50%, in particularfrom 5 to 45%, preferably from 15 to 45%, more preferentially from 20 to45%, where MPMD represents 2-methylpentamethylenediamine (MPMD) and Trepresents terephthalic acid,XT is a unit comprising a major amide moiety present in a molar contentranging from 50 to 95%, in particular from 55 to 95%, preferably from 55to 85%, more preferentially from 55 to 80%, where X is a C₉ to C₁₈,preferably C₉, C₁₀, C₁₁ and C₁₂, linear aliphatic diamine and where T isterephthalic acid,said copolyamide having a melting point: 250° C.<T_(m)≤300° C. asdetermined according to the standard ISO 11357-3 (2013),said structure being devoid of reinforcing fibers.

It has thus been found that these products, originally developed forcomposite applications, owing to their high stiffness (high Tg)/goodprocessability (relatively low Tm) compromise, also have a crystallinestructure better than expectations and can be used as a barrier layer,that is to say a layer with very low permeability to fluids, inparticular motor-vehicle fluids, in particular to fuels, in a structure,in particular a multilayer structure, for fluid transport, although theamine chain end/acid chain end ratio is in particular less than 5.

In other words, said structure is a barrier structure, in particularchosen from bottles, tanks, containers, pipes, receptacles and films,comprising at least one barrier layer (1) comprising an MPMDT/XTcopolyamide as defined above.

The structure of the invention can either consist of a single layer ofthis polyamide, in which case it does not comprise reinforcing fibres,or comprise a layer comprising the MPMDT/XT polyamide (and thereforedevoid of reinforcing fibers) and at least one layer of anothermaterial, it being possible for said at least one other layer tocomprise reinforcing fibers.

In the structure of the invention, the layer comprising the MPMDT/XTpolyamide can also comprise other polymers. By way of example of theseother polymers, mention may be made of polyamides, EVOH, PPS, PPO,polycarbonate and ABS.

The invention also relates to the use of an MPMDT/XT copolyamide with ahigh Tg for producing a structure, in particular a multilayer structure,comprising at least one barrier layer comprising said MPMDT/XTcopolyamide.

The invention also relates to bottles, tanks, containers, pipes andreceptacles of any type manufactured with the above structure. Thisstructure can also be in the form of films with which, for example,packagings are made. All these objects have good barrier properties.

The invention also relates to these objects and also to the use of thesestructures and of these objects.

DETAILED DESCRIPTION OF THE INVENTION

Other features, aspects, subjects and advantages of the presentinvention will emerge even more clearly on reading the description andthe examples that follow.

According to a first aspect of the invention, the invention relates to astructure comprising at least one layer (1) comprising an MPMDT/XTcopolyamide wherein:

-   -   MPMDT is a unit comprising an amide moiety present in a molar        content ranging from 5 to 50%, in particular from 5 to 45%,        preferably from 15 to 45%, more preferentially from 20 to 45%,        where MPMD represents 2-methylpentamethylenediamine (MPMD) and T        represents terephthalic acid,    -   XT is a unit comprising a major amide moiety present in a molar        content ranging from 50 to 95%, in particular from 55 to 95%,        preferably from 55 to 85%, more preferentially from 55 to 80%,        where X is a C₉ to C₁₈, preferably C₉, C₁₀, C₁₁ and C₁₂, linear        aliphatic diamine and where T is terephthalic acid,    -   said copolyamide having a melting point: 250° C.<T_(m)≤300° C.        as determined according to the standard ISO 11357-3 (2013), and        -   in the MPMDT and/or XT units, independently of one another,            up to 30 mol %, relative to the total amount of dicarboxylic            acids, of the terephthalic acid can be replaced with other            aromatic, aliphatic or cycloaliphatic dicarboxylic acids            comprising 6 to 36 carbon atoms, in particular 6 to 14            carbon atoms, and        -   in the MPMDT and/or XT units, independently of one another,            up to 30 mol % of the MPMD and/or where appropriate of X,            relative to the total amount of diamines, can be replaced            with other diamines comprising from 4 to 36 carbon atoms, in            particular 6 to 12 carbon atoms, and        -   in the copolyamide, no more than 30 mol %, relative to the            total amount of monomers, can be formed by lactams or            aminocarboxylic acids, and        -   on the condition that the sum of the monomers which replace            the terephthalic acid, the MPMD and X does not exceed a            concentration of 30 mol %, relative to the total amount of            monomers used in the copolyamide, and        -   on the condition that the MPMD is not totally substituted,    -   said composition being devoid of reinforcing fibers.

Consequently, the invention describes a structure which is at leastmonolayer and the single layer of which is based on MPMDT/XT.

It is quite obvious that, regardless of the present substitution that iscarried out for the diacids and/or diamines, the proportion of MPMDT andof XT remains within the ranges of values indicated. For example, MPMDT,even when it is substituted with a diacid and/or a diamine, is in anycase present in a molar content of at least 5% or of at least 15% or ofat least 20%, depending on the value range claimed.

In the same way, the upper limit of these ranges of values is conserved.

Advantageously, the copolyamide has an amount of amine chain endgroups/amount of acid chain end groups ratio <5, said amount of aminechain end groups and said amount of acid chain groups being determinedby NMR.

Advantageously, MPMDT is present in a molar content of from 5 to 50% andXT is present in a molar content of from 50 to 95%.

Advantageously, MPMDT is present in a molar content of from 15 to 45%and XT is present in a molar content of from 50 to 85%.

Advantageously, MPMDT is present in a molar content of from 20 to 45%and XT is present in a molar content of from 50 to 80%.

Advantageously, MPMDT is present in a molar content of from 5 to 45% andXT is present in a molar content of from 55 to 95%.

Advantageously, MPMDT is present in a molar content of from 15 to 45%and XT is present in a molar content of from 55 to 85%.

Advantageously, MPMDT is present in a molar content of from 20 to 45%and XT is present in a molar content of from 55 to 80%.

MPMD and/or X can be replaced, independently of one another, up to 30mol %, by other diamines defined above, in particular by a linear orbranched aliphatic diamine, a cycloaliphatic diamine or an arylaromaticdiamine.

By way of example, the linear or branched aliphatic diamine is chosenfrom 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine,1,8-octanediamine (OMDA), 1,9-nonanediamine (NMDA),2-methyl-1,8-octanediamine (MODA), 2,2,4-trimethylhexamethylenediamine(TMHMD), 2,4,4-trimethylhexamethylenediamine (TMHMD),5-methyl-1,9-nonanediamine, 1,11-undecanediamine,2-butyl-2-ethyl-1,5-pentanediamine, 1,12-dodecanediamine,1,13-tridecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamineand 1,18-octadecanediamine.

The cycloaliphatic diamine can be chosen from cyclohexanediamine,1,3-bis(aminomethyl)cyclohexane (BAC), 1,4-bis(aminomethyl)cyclohexane(BAC), isophoronediamine, norbornanedimethylamine,4,4′-diaminodicyclohexylmethane (PACM),2,2-(4,4′-diaminodicyclohexyl)propane (PACP) and3,3′-dimethyl-4,4′-diaminodicyclohexylmethane (MACM).

The arylaromatic diamine may be m-xylenediamine.

T can be replaced, up to 30 mol %, by other dicarboxylic acids definedabove, in particular by other aromatic, aliphatic or cycloaliphaticdicarboxylic acids.

The aromatic dicarboxylic acids can be chosen fromnaphthalenedicarboxylic acid (NDA) and isophthalic acid (IPS).

The aliphatic dicarboxylic acids can be chosen from adipic acid, subericacid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioicacid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid,hexadecanedioic acid, octadecanedioic acid and dimerized fatty acids.

The cycloaliphatic dicarboxylic acids can be chosen from cis- and/ortrans-1,4cyclohexane-dicarboxylic acid and/or cis- and/ortrans-1,3cyclohexane-dicarboxylic acid (CHDA).

MPMD and/or X and/or T can be replaced, independently of one another, upto 30 mol %, by lactams or aminocarboxylic acids.

The lactams and aminocarboxylic acids can be chosen from caprolactam(CL), α,ω-aminocaproic acid, α,ω-aminononanoic acid, α,ω-aminoundecanoicacid (AUA), lauryllactam (LL) and α,ω-aminododecanoic acid (ADA).

A maximum of 30 mol %, relative to the total sum of the MPMD, X and Tmonomers, of replacement, whether it is with another diamine, anotherdiacid, a lactam or an aminocarboxylic acid, or any mixture thereof, ispossible.

Advantageously, a maximum of 20 mol %, relative to the total sum of theMPMD, X and T monomers, of replacement, whether it is with anotherdiamine, another diacid, a lactam or an aminocarboxylic acid, or anymixture thereof, is possible.

Advantageously, a maximum of 10 mol %, relative to the total sum of theMPMD, X and T monomers, of replacement, whether it is with anotherdiamine, another diacid, a lactam or an aminocarboxylic acid, or anymixture thereof, is possible.

Advantageously, X is a C₉ to C₁₈ diamine.

Advantageously, X is a C₉ to C₁₈ diamine and MPMDT is present in a molarcontent of from 5 to 50% and XT is present in a molar amount of from 50to 95%.

Advantageously, X is a C₉ to C₁₈ diamine and MPMDT is present in a molarcontent of from 5 to 45% and XT is present in a molar amount of from 55to 95%.

Advantageously, X is a C₉ to C₁₈ diamine and MPMDT is present in a molarcontent of from 15 to 45% and XT is present in a molar amount of from 55to 85%.

Advantageously, X is a C₉ to C₁₈ diamine and MPMDT is present in a molarcontent of from 20 to 45% and XT is present in a molar amount of from 55to 80%.

Advantageously, X is a C₉, C₁₀, C₁₁, C₁₂ diamine.

Advantageously, X is a C₉, C₁₀, C₁₁, C₁₂ diamine and MPMDT is present ina molar content of from 5 to 50% and XT is present in a molar amount offrom 50 to 95%.

Advantageously, X is a C₉, C₁₀, C₁₁, C₁₂ diamine and MPMDT is present ina molar content of from 5 to 45% and XT is present in a molar amount offrom 55 to 95%.

Advantageously, X is a C₉, C₁₀, C₁₁, C₁₂ diamine and MPMDT is present ina molar content of from 15 to 45% and XT is present in a molar amount offrom 55 to 85%.

Advantageously, X is a C₉, C₁₀, C₁₁, C₁₂ diamine and MPMDT is present ina molar content of from 20 to 45% and XT is present in a molar amount offrom 55 to 80%.

Advantageously, X is a C₉ diamine and MPMDT is present in a molarcontent of from 5 to 50% and XT is present in a molar amount of from 50to 95%.

Advantageously, X is a C₉ diamine and MPMDT is present in a molarcontent of from 5 to 45% and XT is present in a molar amount of from 55to 95%.

Advantageously, X is a C₉ diamine and MPMDT is present in a molarcontent of from 15 to 45% and XT is present in a molar amount of from 55to 85%.

Advantageously, X is a C₉ diamine and MPMDT is present in a molarcontent of from 20 to 45% and XT is present in a molar amount of from 55to 80%.

Advantageously, X is a C₁₀ diamine and MPMDT is present in a molarcontent of from 5 to 50% and XT is present in a molar amount of from 50to 95%.

Advantageously, X is a C₁₀ diamine and MPMDT is present in a molarcontent of from 5 to 45% and XT is present in a molar amount of from 55to 95%.

Advantageously, X is a C₁₀ diamine and MPMDT is present in a molarcontent of from 15 to 45% and XT is present in a molar amount of from 55to 85%.

Advantageously, X is a C₁₀ diamine and MPMDT is present in a molarcontent of from 20 to 45% and XT is present in a molar amount of from 55to 80%.

Advantageously, X is a C₁₁ diamine and MPMDT is present in a molarcontent of from 5 to 50% and XT is present in a molar amount of from 50to 95%.

Advantageously, X is a C₁₁ diamine and MPMDT is present in a molarcontent of from 5 to 45% and XT is present in a molar amount of from 55to 95%.

Advantageously, X is a C₁₁ diamine and MPMDT is present in a molarcontent of from 15 to 45% and XT is present in a molar amount of from 55to 85%.

Advantageously, X is a C₁₁ diamine and MPMDT is present in a molarcontent of from 20 to 45% and XT is present in a molar amount of from 55to 80%.

Advantageously, X is a C₁₂ diamine and MPMDT is present in a molarcontent of from 5 to 50% and XT is present in a molar amount of from 50to 95%.

Advantageously, X is a C₁₂ diamine and MPMDT is present in a molarcontent of from 5 to 45% and XT is present in a molar amount of from 55to 95%.

Advantageously, X is a C₁₂ diamine and MPMDT is present in a molarcontent of from 15 to 45% and XT is present in a molar amount of from 55to 85%.

Advantageously, X is a C₁₂ diamine and MPMDT is present in a molarcontent of from 20 to 45% and XT is present in a molar amount of from 55to 80%.

The expression “reinforcing fibers” or “fibrous reinforcement” denotesan assembly of short or long fibers. The fibers may be continuous, or inthe form of unidirectional (UD) or multidirectional (2D, 3D)reinforcement, in the form of fabrics, sheets, strips or braids and canalso be cut for example in the form of nonwovens (mats) or in the formof felts.

The expression “reinforcing fibers” denotes in particular:

-   -   mineral fibers, in particular carbon fibers, which include        fibers of nanotubes or carbon nanotubes (CNTs), carbon        nanofibers or graphenes; silica fibers such as glass fibers, in        particular of E, R or S2 type; boron fibers; ceramic fibers, in        particular silicon carbide fibers, boron carbide fibers, boron        carbonitride fibers, silicon nitride fibers, boron nitride        fibers, basalt fibers; fibers or filaments based on metals        and/or alloys thereof; fibers of metal oxides, in particular of        alumina (Al₂O₃); metalized fibers such as metalized glass fibers        and metalized carbon fibers, or mixtures of the abovementioned        fibers;    -   polymeric or polymer fibers, in particular:        -   fibers of thermosetting polymer and more particularly those            chosen from: unsaturated polyesters, epoxy resins, vinyl            esters, phenolic resins, polyurethanes, cyanoacrylates and            polyimides, such as bismaleimide resins, or aminoplasts            resulting from the reaction of an amine such as melamine            with an aldehyde such as glyoxal or formaldehyde,        -   fibers of thermoplastic polymer and more particularly chosen            from: polyethylene terephthalate (PET), polybutylene            terephthalate (PBT), high-density polyolefins such as            polyethylene (PE), polypropylene (PP) and PET/PP copolymers,            or PVOH (polyvinyl alcohol),        -   fibers of polyamides corresponding to one of the formulae:            6, 11, 12, 610, 612, 66, 4.6,        -   fibers of aramids (such as Kevlar) and aromatic polyamides            such as those corresponding to one of the formulae: PPDT,            MPDI, PAA and PPA, with PPD and MPD being respectively p-            and m-phenylenediamine, PAA being polyarylamides and PPA            being polyphthalamides,        -   fibers of polyamide block copolymers such as            polyamide/polyether, fibers of polyaryl ether ketones            (PAEKs) such as polyether ether ketone (PEEK), polyether            ketone ketone (PEKK) or polyether ketone ether ketone ketone            (PEKEKK),    -   or mixtures of the abovementioned fibers.

Consequently, all the reinforcing fibers defined above are excluded fromthe scope of the invention.

Advantageously, the amount of amine chain end is from 5 mmol/kg to 100mmol/kg, preferentially from 20 mmol/kg to 80 mmol/kg and even morepreferentially from 30 mmol/kg to 60 mmol/kg.

Advantageously, the amount of acid chain end is from 5 mmol/kg to 100mmol/kg, preferentially from 20 mmol/kg to 80 mmol/kg and even morepreferentially from 30 mmol/kg to 60 mmol/kg.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein said copolyamide defined above has aglass transition temperature Tg≥125° C., in particular a glasstransition temperature Tg>125° C., determined according to the standardISO 11357-2:2013.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein X is 1,10-decanediamine.

Advantageously, X is 1,10-decanediamine and MPMDT is present in a molarcontent of from 5 to 50% and XT is present in a molar amount of from 50to 95%.

Advantageously, X is 1,10-decanediamine and MPMDT is present in a molarcontent of from 5 to 45% and XT is present in a molar amount of from 55to 95%.

Advantageously, X is 1,10-decanediamine and MPMDT is present in a molarcontent of from 15 to 45% and XT is present in a molar amount of from 55to 85%.

Advantageously, X is 1,10-decanediamine and MPMDT is present in a molarcontent of from 20 to 45% and XT is present in a molar amount of from 55to 80%.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein none of the monomers of saidcopolyamide is substituted with another diamine, another dicarboxylicacid or a lactam.

The structure wherein none of the monomers is substituted is thereforeof formula MPMDT/XT without any other presence of other diamine, ofother dicarboxylic acid, of lactam or of aminocarboxylic acid.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein said layer (1) comprises an impactmodifier and/or a modifier of core-shell type.

The term “impact modifier” should be understood as meaning apolyolefin-based polymer with a flexural modulus of less than 100 MPameasured according to standard ISO-178:2010 and a Tg of less than 0° C.(measured according to standard 11357-2: 2013 at the inflection point ofthe DSC thermogram), in particular a polyolefin, optionally coupled witha PEBA (pether-block-amide) having a flexural modulus <200 MPa.

In this advantageous embodiment, this polyolefin-based polymer istherefore present in the coployamide constituting the layer (1).

The polyolefin of the impact modifier may be functionalized ornonfunctionalized or be a mixture of at least one which isfunctionalized and/or at least one which is nonfunctionalized.

In particular, a portion or all of the polyolefins bears a functionchosen from carboxylic acid, carboxylic anhydride and epoxide functions,and is in particular chosen from a copolymer of ethylene and propylenewith elastomeric character (EPR), an ethylene-propylene-diene copolymerwith elastomeric character (EPDM) and an ethylene/alkyl (meth)acrylatecopolymer, an ethylene-higher alkene copolymer, in particular anethylene-octene copolymer, or an ethylene-alkyl acrylate-maleicanhydride terpolymer.

Advantageously, the impact modifier is chosen from Fusabond F493, aLotader®, in particular Lotader 5500 or Lotader 7500, Escor VA1801 orVA1803, Excelsior E1040, Amplify GR216, Tafmer MH5020 or Orevac IM800 ora mixture thereof; in this case they are in a ratio ranging from0.1/99.9 to 99.9/0.1, preferentially 1/2 to 2/1 when they are in amixture of two.

By way of example, the impact modifier is chosen from the followingmixtures: F493/Lotader®, in particular F493/Lotader® 5500 orF493/Lotader® 7500.

The term “modifier of core-shell type” is also denoted “copolymer ofcore-shell type”.

The “modifier of core-shell type” is in the form of fine particles withan elastomer core and at least one thermoplastic shell; the size of theparticles is generally less than a micrometer and advantageously between150 and 500 nm.

The “modifier of core-shell type” has an acrylic or butadiene base,unlike the impact modifier which has a polyolefin base.

Examples of cores that may be mentioned include isoprene or butadienehomopolymers, copolymers of isoprene with not more than 30 mol % of avinyl monomer and copolymers of butadiene with not more than 30 mol % ofa vinyl monomer. The vinyl monomer may be styrene, an alkylstyrene,acrylonitrile or an alkyl (meth)acrylate. Another core family consistsof homopolymers of an alkyl (meth)acrylate and copolymers of alkyl(meth)acrylate with not more than 30 mol % of a vinyl monomer. The alkyl(meth)acrylate is advantageously butyl acrylate. The vinyl monomer maybe styrene, an alkylstyrene, acrylonitrile, butadiene or isoprene. Thecore of the copolymer (A) may be totally or partly crosslinked. Itsuffices to add at least difunctional monomers in the course ofpreparation of the core; these monomers may be chosen frompoly(meth)acrylic esters of polyols such as butylene di(meth)acrylateand trimethylolpropane trimethacrylate. Other difunctional monomers are,for example, divinylbenzene, trivinylbenzene, vinyl acrylate and vinylmethacrylate. The core may also be crosslinked by introducing therein,by grafting or as comonomer during the polymerization, unsaturatedfunctional monomers such as unsaturated carboxylic acid anhydrides,unsaturated carboxylic acids and unsaturated epoxides. Examples that maybe mentioned include maleic anhydride, (meth)acrylic acid and glycidylmethacrylate.

The shell(s) are homopolymers of styrene, of an alkylstyrene or ofmethyl methacrylate or copolymers comprising at least 70 mol % of one ofthese preceding monomers and at least one comonomer chosen from theother preceding monomers, vinyl acetate and acrylonitrile. The shell mayalso be functionalized by introducing therein, by grafting or ascomonomer during the polymerization, unsaturated functional monomerssuch as unsaturated carboxylic acid anhydrides, unsaturated carboxylicacids and unsaturated epoxides. Examples that may be mentioned includemaleic anhydride, (meth)acrylic acid and glycidyl methacrylate. By wayof example, mention may be made of core-shell copolymers (A) having apolystyrene shell and core-shell copolymers (A) having a PMMA shell.Core-shell copolymers (A) having two shells, one made of polystyrene andthe exterior one made of PMMA, also exist. Examples of copolymer (A) andalso the process for preparing them are described in the followingpatents: U.S. Pat. No. 4,180,494, U.S. Pat. No. 3,808,180, U.S. Pat. No.4,096,202, U.S. Pat. No. 4,260,693, U.S. Pat. No. 3,287,443, U.S. Pat.No. 3,657,391, U.S. Pat. No. 4,299,928, U.S. Pat. No. 3,985,704.

The “modifier of core-shell type” is thus different than the polyolefinof the impact modifier, especially in that the impact modifier reactswith the polyamide matrix, whereas the core-shell does not reacttherewith since the core of the latter is capable of reacting only withthe shell thereof.

Advantageously, the impact modifier and/or the modifier of core-shelltype is present at from 5 to 35% by weight relative to the weight of allthe constituents of the copolyamide of the layer (1), in particular from5 to 25% and more particularly from 5 to 15%.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 35% by weightrelative to the weight of all the constituents of the copolyamide, inparticular from 5 to 25% and more particularly from 5 to 15%.

Advantageously, in the structures comprising an impact modifier and/or amodifier of co-shell type, X is 1,10-decanediamine.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein said structure consists of a singlelayer (1).

The invention therefore in this case relates to a monolayer pipe and, inthis embodiment, no other layer is present.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein said layer (1) comprises astabilizer chosen from an organic stabilizer, an inorganic stabilizer,in particular a copper-based stabilizer, and a mixture thereof.

The expression “organic stabilizer” or more generally a “combination oforganic stabilizers”, denotes a primary antioxidant of phenol type, asecondary antioxidant of phosphite type, or even optionally otherstabilizers, such as a HALS, which means Hindered Amine Light Stabilizer(for example Tinuvin 770 from the company Ciba), a UV stabilizer (forexample Tinuvin 312 from the company Ciba), a phenolic stabilizer or aphosphorus-based stabilizer. Use may also be made of antioxidants ofamine type, such as Naugard 445 from the company Crompton or elsepolyfunctional stabilizers, such as Nylostab S-EED from the companyClariant.

The organic stabilizer present within the layer (1) can be chosen,without this list being restrictive, from:

-   -   phenolic antioxidants, for example Irganox 245, Irganox 1010,        Irganox 1098 from the company Ciba, Irganox MD1024 from the        company Ciba, Lowinox 44B25 from the company Great Lakes, ADK        Stab AO-80 from a company Adeka Palmarole,    -   phosphorus-based stabilizers, such as phosphites, for example        Irgafos 168 from the company Ciba,    -   a UV absorber, such as Tinuvin 312 from the company Ciba,    -   a HALS, as previously mentioned,    -   a stabilizer of amine type, such as Naugard 445 from the company        Crompton, or else of hindered amine type, such as Tinuvin 770        from the company Ciba,    -   a polyfunctional stabilizer, such as Nylostab S-EED from the        company Clariant.

It is of course possible to envision a mixture of two, or more, of theseorganic stabilizers.

Preferably, the organic stabilizer is present within the copolyamide ofthe layer (1) of the structure in a content of between 0.3 and 3% byweight relative to the total weight of the constituents of thecopolyamide.

The expression “inorganic stabilizer” denotes a copper-based stabilizer.By way of example of such inorganic stabilizers, mention may be made ofcopper acetate and halides. Incidentally, other metals, such as silver,can optionally be considered, but said metals are known to be lesseffective. These copper-based compounds are typically combined withalkali metal halides, in particular potassium halides.

These inorganic stabilizers are more particularly used when thestructures must have an improved long-term heat resistance in hot air,in particular for temperatures greater than or equal to 100-120° C.,since they tend to prevent polymer chain cleavages.

More particularly, the term “copper-based stabilizer” is intended tomean a compound comprising at least one copper atom, in particular inionic or ionizable form, for example in complex form.

The copper-based stabilizer present within the layer (1) can be chosenfrom cuprous chloride, cupric chloride, cuprous bromide, cupric bromide,cuprous iodide, cupric iodide, cuprous acetate and cupric acetate.Mention may be made of halides or acetates of other metals, such assilver, in combination with the copper-based stabilizer. Thesecopper-based compounds are typically combined with alkali metal halides.A well-known example is the mixture of CuI and KI, where the CuI:KIratio is typically between 1:5 and 1:15. An example of such a stabilizeris Polyadd P201 from the company Ciba.

Fuller details with regard to copper-based stabilizers will be found inthe patent U.S. Pat. No. 2,705,227. Copper-based stabilizers, such ascomplexed coppers, have more recently emerged, for instance BruggolenH3336, H3337, H3373 from the company Brüggemann.

Advantageously, the copper-based stabilizer is chosen from copperhalides, copper acetate, copper halides or copper acetate as a mixturewith at least one alkali metal halide, and mixtures thereof, preferablymixtures of copper iodide and potassium iodide (CuI/KI).

Preferably, the copper-based stabilizer is present in the layer (1) ofthe structure in a content of between 0.05 and 1.5% by weight relativeto the total weight of the constituents of the copolyamide.

Preferably, the copper (1) comprises, in addition, no other transitionmetals.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 35% by weightrelative to the weight of all the constituents of the copolyamide and anorganic stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 35% by weightrelative to the weight of all the constituents of the copolyamide and aninorganic stabilizer, in particular a copper-based stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 35% by weightrelative to the weight of all the constituents of the copolyamide and amixture of organic stabilizer and of inorganic stabilizer, in particulara copper-based stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 25% by weightrelative to the weight of all the constituents of the copolyamide and anorganic stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 25% by weightrelative to the weight of all the constituents of the copolyamide and aninorganic stabilizer, in particular a copper-based stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 25% by weightrelative to the weight of all the constituents of the copolyamide and amixture of organic stabilizer and of inorganic stabilizer, in particulara copper-based stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 15% by weightrelative to the weight of all the constituents of the copolyamide and anorganic stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 15% by weightrelative to the weight of all the constituents of the copolyamide and aninorganic stabilizer, in particular a copper-based stabilizer.

Advantageously, the invention therefore relates to a structure asdefined above, comprising at least one layer (1) comprising an MPMDT/XTcopolyamide as defined above and comprising an impact modifier and/or amodifier of core-shell type in a proportion of from 5 to 15% by weightrelative to the weight of all the constituents of the copolyamide and amixture of organic stabilizer and of inorganic stabilizer, in particulara copper-based stabilizer.

Advantageously, in the structures comprising an impact modifier and/or amodifier of core-shell type and a stabilizer, X is 1,10-decanediamine.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein said layer (1) comprises anantistatic filler chosen from carbon black, graphite, carbon fibers andcarbon nanotubes, in particular carbon black and carbon nanotubes.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein said layer (1) can comprise at leastone additive chosen from an antioxidant, a heat stabilizer, a UVabsorber, a light stabilizer, a lubricant, a mineral filler, a flameretardant, a nucleating agent, a plasticizer and a dye.

The reinforcing fibers are excluded from the additives, and inparticular the term “mineral filler” excludes the reinforcing fibers.

Advantageously, the additive(s) are present in the layer (1) in a weightproportion of from 1 to 20%, in particular from 5 to 15%, relative tothe total weight of the constituents of the layer (1).

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present, thelayers (1) and (2) being capable of adhering to one another.

The expression “being capable of adhering to one another” means that, ifthe structure consists of two layers, the layers (1) and (2) at leastpartially adhere to one another.

If the structure comprises at least one third layer, said third layercan be placed between the layer (1) and the layer (2), in which case thelayers (1) and (2) do not adhere to one another but, on the other hand,the layers (1) and (3) adhere to one another, as do the layers (3) and(2).

Advantageously, the structure consists of two layers (1) and (2) whichadhere to one another.

Advantageously, said layer (2) comprises at least one polyamide chosenfrom an aliphatic polyamide and an aromatic polyamide, in particular analiphatic polyamide.

Advantageously, said aliphatic polyamide results from thepolycondensation of at least one lactam or of at least oneaminocarboxylic acid, or of a diamine and of a dicarboxylic acid, or ofa mixture thereof, the diamine being chosen from an aliphatic diamineand a cycloaliphatic diamine and the dicarboxylic acid being chosen froman aliphatic diacid and a cycloaliphatic diacid, or a mixture thereof.

The aminocarboxylic acid can be chosen from 9-aminononanoic acid,10-aminodecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoicacid and derivatives thereof, in particular N-heptyl-11-aminoundecanoicacid, advantageously 12-aminododecanoic acid and 11-aminoundecanoicacid.

The lactam can be chosen from pyrrolidinone, 2-piperidinone,caprolactam, enantholactam, caprylolactam, pelargolactam, decanolactam,undecanolactam and lauryllactam, advantageously undecanolactam andlauryllactam.

When the diamine is aliphatic and linear, it has the formulaH₂N—(CH₂)_(a)—NH₂. The diacid may be aliphatic (in particular linearaliphatic), cycloaliphatic or aromatic.

Preferentially, when the diamine is linear and aliphatic, it is chosenfrom butanediamine (a=4), pentanediamine (a=5), hexanediamine (a=6),heptanediamine (a=7), octanediamine (a=8), nonanediamine (a=9),decanediamine (a=10), undecanediamine (a=11), dodecanediamine (a=12),tridecanediamine (a=13), tetradecanediamine (a=14), hexadecanediamine(a=16), octadecanediamine (a=18), octadecanediamine (a=18),eicosanediamine (a=20), docosanediamine (a=22) and diamines obtainedfrom dimerized fatty acids.

When the diamine is cycloaliphatic, it is preferably chosen from thosecomprising two rings. They in particular correspond to the followinggeneral formula:

in which:

-   -   R₁, R₂, R₃ and R₄ independently represent a group chosen from a        hydrogen atom or an alkyl having from 1 to 6 carbon atoms and    -   X represents either a single bond, or a divalent group        consisting:        -   of a linear or branched aliphatic chain comprising from 1 to            10 carbon atoms, optionally substituted by cycloaliphatic or            aromatic groups having from 6 to 8 carbon atoms,        -   of a cycloaliphatic group having from 6 to 12 carbon atoms.            More preferentially, the Ca cycloaliphatic diamine of the            polyamide is chosen from            bis(3,5-dialkyl-4-aminocyclohexyl)methane,            bis(3,5-dialkyl-4-aminocyclohexyl)ethane,            bis(3,5-dialkyl-4-aminocyclohexyl)propane,            bis(3,5-dialkyl-4-aminocyclohexyl)butane,            bis-(3-methyl-4-aminocyclohexyl)methane (noted BMACM, MACM            or B), p-bis(aminocyclohexyl)methane (PACM) and            isopropylidenedi(cyclohexylamine) (PACP).

A nonexhaustive list of these cycloaliphatic diamines is given in thepublication “Cycloaliphatic Amines” (Encyclopedia of ChemicalTechnology, Kirk-Othmer, 4th Edition (1992), pp. 386-405).

The aliphatic and linear dicarboxylic acid is chosen from succinic acid(b=4), pentanedioic acid (b=5), adipic acid (b=6), heptanedioic acid(b=7), octanedioic acid (b=8), azelaic acid (b=9), sebacic acid (b=10),undecanedioic acid (b=11), dodecanedioic acid (b=12), brassylic acid(b=13), tetradecanedioic acid (b=14), hexadecanedioic acid (b=16),octadecanoic acid (b=18), octadecenedioic acid (b=18), eicosanedioicacid (b=20), docosanedioic acid (b=22) and fatty acid dimers containing36 carbons.

The fatty acid dimers mentioned above are dimerized fatty acids obtainedby oligomerization or polymerization of unsaturated monobasic fattyacids bearing a long hydrocarbon chain (such as linoleic acid and oleicacid), as described in particular in document EP 0 471 566.

When the diacid is cycloaliphatic, it may comprise the following carbonbackbones: norbornylmethane, cyclohexylmethane, dicyclohexylmethane,dicyclohexylpropane, di(methylcyclohexyl)propane.

The polyamide of the layer (2) may be a homopolyamide or a copolyamide.

The nomenclature used to define the polyamides is described in thestandard ISO 16396-1: 2015 “Plastics—Polyamide (PA) molding andextrusion materials—Part 1: Designation system, marking of products andbasis for specifications”.

Advantageously, the polyamide of the layer (2) is chosen from PA11,PA12, PA1010, PA1012, PA610 and PA612.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein another polyamide, different thanthat of the layer (2) can be present in the layer (2).

Said other polyamide is as defined above in the layer (2) on thecondition that it is different than that of the layer (2).

Advantageously, a plasticizer is present in the layer (2).

Advantageously, the plasticizer of the layer (2) is present at from 1 to20%, in particular from 5 to 15%, by weight relative to the weight ofall the constituents of the copolyamide of the layer (2).

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein an impact modifier and/or a modifierof core-shell type is present in the layer (2).

The impact modifier and/or the modifier of core-shell type are asdefined above.

Advantageously, the impact modifier and/or the modifier of core-shelltype is present at from 5 to 35% by weight relative to the weight of allthe constituents of the copolyamide of the layer (2), in particular from5 to 25% and more particularly from 5 to 15%.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present, thelayers (1) and (2) adhering to one another, the layer (1) being one ofthose defined above, and the layer (2) optionally comprising anotherpolyamide, the layer (2) comprising a plasticizer at from 1 to 20% byweight and an impact modifier and/or a modifier of core-shell type in aproportion of from 5 to 35% by weight relative to the weight of all theconstituents of the copolyamide of the layer (2).

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present, thelayers (1) and (2) adhering to one another, the layer (1) being one ofthose defined above, and the layer (2) optionally comprising anotherpolyamide, the layer (2) comprising a plasticizer at from 1 to 20% byweight and an impact modifier and/or a modifier of core-shell type in aproportion of from 5 to 25% by weight relative to the weight of all theconstituents of the copolyamide of the layer (2).

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present, thelayers (1) and (2) adhering to one another, the layer (1) being one ofthose defined above, and the layer (2) optionally comprising anotherpolyamide, the layer (2) comprising a plasticizer at from 5 to 15% byweight and an impact modifier and/or a modifier of core-shell type in aproportion of from 5 to 35% by weight relative to the weight of all theconstituents of the copolyamide of the layer (2).

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present, thelayers (1) and (2) adhering to one another, the layer (1) being one ofthose defined above, and the layer (2) optionally comprising anotherpolyamide, the layer (2) comprising a plasticizer at from 5 to 15% byweight and an impact modifier and/or a modifier of core-shell type in aproportion of from 5 to 25% by weight relative to the weight of all theconstituents of the copolyamide of the layer (2).

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present,wherein said layer (2) comprises a stabilizer chosen from an organicstabilizer, an inorganic stabilizer, in particular a copper-basedstabilizer, and a mixture thereof.

The stabilizers are as defined above.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present,wherein the layer (1) comprises an organic stabilizer and the layer (2)comprises an inorganic stabilizer, in particular a copper-basedstabilizer.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present,wherein the layer (1) comprises an inorganic stabilizer, in particular acopper-based stabilizer, and the layer (2) comprises an organicstabilizer.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present,wherein said layer (2) comprises an antistatic filler chosen from carbonblack, graphite, carbon fibers and carbon nanotubes, in particularcarbon black and carbon nanotubes.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein a second layer (2) is present,wherein said layer (2) can comprise at least one additive chosen from anantioxidant, a heat stabilizer, a UV absorber, a light stabilizer, alubricant, a mineral filler, a flame retardant, a nucleating agent and adye.

In one advantageous embodiment, the present invention relates to astructure as defined above, wherein the layer (1) is a barrier layer, inparticular a barrier to a fluid, said fluid being chosen from a fuel,said fuel being a gasoline, in particular a biogasoline (mixture ofgasoline and of alcohol, in particular of methanol or ethanol), ordiesel, in particular biodiesel, an oil, a brake fluid, urea solutions,a glycol-based cooling fluid, a gas, in particular compressed air, andsaid barrier layer (1) is in contact with the fluid.

The structure defined in this embodiment therefore comprises at leastone layer (1) and can therefore be a monolayer or bilayer (1) and (2),but should the structure comprise other layers, this would not departfrom the context of the invention.

Advantageously, the structure consists of two layers (1) and (2) and thelayer (1) is the barrier layer.

Consequently, in the case where the structure comprises two layers, itcomprises, from the outside to the inside, the following layers:(2)//(1).

In the case where the structure comprises at least one other layer, thelatter cannot be in contact with the fluid.

In one advantageous embodiment, the present invention relates to astructure comprising at least one layer (1) as defined above, and asecond layer (2) as defined above, the layers (1) and (2) being capableof adhering to one another,

additionally comprising a layer (3), the layer (3) being identical to ordifferent than the layer (1).In this embodiment, the structure comprises or consists of the followinglayers, from the outside to the inside:(3)//(2)//(1) or (2)//(3)//(1).

Advantageously, the layer (3) is different than the layer (1) and is atie layer and the structure comprises, from the outside to the inside,the following layers: (2)//(3)//(1), the layer (1) being in contact withthe fluid.

Advantageously, in the structure (2)//(3)//(1), the layer (1) has athickness of from 100 to 300 μm, in particular from 200 to 300 μm, inparticular 250 μm, the layer (3) has a thickness of from 50 to 100 μm orfrom 100 to 200 μm, in particular 150 μm and the layer (2) as athickness of from 50 to 800 μm, in particular from 50 to 200 μm or from500 to 700 μm.

The tie layer can be a mixture of at least one polyamide having anaverage number of carbon atoms per nitrogen atom noted of between 4 and8.5, advantageously between 4 and 7; at least one polyamide having amelting point greater than or equal to 180° C. and an average number ofcarbon atoms per nitrogen atom of between 7 and 10, advantageouslybetween 7.5 and 9.5, and at least one polyamide having an average numberof carbon atoms per nitrogen atom of between 9 and 18, advantageouslybetween 10 and 18, in particular as defined in document WO 09/122060.

In one advantageous embodiment, the present invention relates to astructure comprising at least one layer (1) as defined above, a secondlayer (2) as defined above, the layers (1) and (2) being capable ofadhering to one another, and a layer (3), the layer (3) being identicalto or different than the layer (1),

said structure additionally comprising at least one other layer (4), thelayer (1) being in contact with the fluid.

Advantageously, the layer (4) is a layer of EVOH.

In one advantageous embodiment, the present invention relates to astructure comprising at least one layer (1) as defined above, and asecond layer (2) as defined above, the layers (1) and (2) being capableof adhering to one another, and a layer (3), the layer (3) beingidentical to or different than the layer (1), and at least one otherlayer (4), the layer (1) being in contact with the fluid, said structurecomprising, from the outside to the inside, the following layers:(2)//(4)//(3)//(1), the layer (1) being in contact with the fluid.

Advantageously, in the structure (2)//(4)//(3)//(1), the layer (3) is atie layer as defined above.

Advantageously, in the structure (2)//(4)//(3)//(1), the layer (4) is alayer of EVOH as defined above.

Advantageously, in the structure (2)//(4)//(3)//(1), the layer (3) is atie layer as defined above and the layer (4) is a layer of EVOH asdefined above.

Advantageously, the structure consists of the layers (2)//(4)//(3)//(1)as defined above.

In one advantageous embodiment, the present invention relates to astructure comprising at least one layer (1) as defined above, a secondlayer (2) as defined above, the layers (1) and (2) being capable ofadhering to one another, a layer (3), the layer (3) being identical toor different than the layer (1), at least one other layer (4), the layer(1) being in contact with the fluid, and comprising, from the outside tothe inside, the following layers: (2)//(4)//(3)//(1), the layer (1)being in contact with the fluid.

Said structure additionally comprising a tie layer (3′), identical to ordifferent than the tie layer (3), is present.

The layer (3′) is therefore a tie of the same type as that defined abovefor the layer (3), but of identical or different composition.

Advantageously, said structure additionally comprising a tie layer (3′)comprises, from the outside to the inside, the following layers:(2)//(3′)//(4)//(3)//(1), the layer (1) being in contact with the fluid.

Advantageously, the layer (1) has a thickness of from 100 to 200 μm, inparticular 150 μm, the layer (2) has a thickness of from 100 to 200 μm,in particular 150 μm, the layer (3) has a thickness of from 200 to 400μm, in particular 300 μm, the layer (3′) has a thickness of from 200 to400 μm, in particular 300 μm, and the layer (4) has a thickness of from50 μm to 150 μm, in particular 100 μm.

According to another aspect, the present invention relates to bottles,tanks, containers, pipes and receptacles manufactured with one of thestructures as defined above.

According to another aspect, the present invention relates to packagingsconsisting of the films manufactured with one of the structures asdefined above.

According to another aspect, the present invention relates to the use ofan MPMDT/XT polyamide wherein:

-   -   MPMDT is a unit comprising an amide moiety present in a molar        content ranging from 5 to 50%, in particular from 5 to 45%,        preferably from 15 to 45%, more preferentially from 20 to 45%,        where MPMD represents 2-methylpentamethylenediamine (MPMD) and T        represents terephthalic acid,    -   XT is a unit comprising a major amide moiety present in a molar        content ranging from 50 to 95%, in particular from 55 to 95%,        preferably from 55 to 85%, more preferentially from 55 to 80%,        where X is a C₉ to C₁₈, preferably C₉, C₁₀, C₁₁ and C₁₂, linear        aliphatic diamine and where T is terephthalic acid,    -   said copolyamide having a melting point: 250° C.<T_(m)≤300° C.        as determined according to the standard ISO 11357-3 (2013),        -   in the MPMDT and/or XT units, independently of one another,            up to 30 mol %, relative to the total amount of dicarboxylic            acids, of the terephthalic acid can be replaced with other            aromatic, aliphatic or cycloaliphatic dicarboxylic acids            comprising 6 to 36 carbon atoms, in particular 6 to 14            carbon atoms, and        -   in the MPMDT and/or XT units, independently of one another,            up to 30 mol % of the MPMD and/or where appropriate of X,            relative to the total amount of diamines, can be replaced            with other diamines comprising from 4 to 36 carbon atoms, in            particular 6 to 12 carbon atoms, and        -   in the copolyamide, no more than 30 mol %, relative to the            total amount of monomers, can be formed by lactams or            aminocarboxylic acids, and        -   on the condition that the sum of the monomers which replace            the terephthalic acid, the MPMD and X does not exceed a            concentration of 30 mol %, relative to the total amount of            monomers used in the copolyamide, and        -   on the condition that the MPMD is not totally substituted,            for the production of a structure, in particular a            multilayer structure, comprising at least one barrier            layer (1) comprising said MPMDT/XT polyamide,    -   said composition being devoid of reinforcing fibers.

All the features and all the embodiments defined above for thestructures can apply for the use defined above.

EXAMPLES

1) Preparation of an MPMDT/10T and of Comparative Polyamides

5 kg of the following starting materials are introduced into a 14-literautoclave reactor:

-   -   500 g of water,    -   the diamine or diamines,    -   the amino acid (optionally),    -   the diacid or diacids,    -   the monofunctional chain regulator: benzoic acid or stearic acid        in an amount suitable for the intended viscosity,    -   35 g of sodium hypophosphite in solution,    -   0.1 g of a Wacker AK1000 antifoaming agent (Wacker Silicones).

The nature and molar ratios of the molecular structures and moieties ofthe polyamides (by referenced test) are given in table 1 below.

The closed reactor is purged of its residual oxygen and then heated to atemperature of 230° C. with respect to the material introduced. Afterstirring for 30 minutes under these conditions, the pressurized vaporwhich has formed in the reactor is gradually reduced in pressure over 60minutes, while gradually increasing the material temperature so that itbecomes established at Tm+10° C. at atmospheric pressure. Thepolymerization is then continued under nitrogen flushing of 20 I/h untilthe intended viscosity shown in the characteristics table is obtained.

The polymer is subsequently emptied out via the bottom valve, thencooled in a water trough and then granulated.

The products are then injection-molded in the form of 100 mm×100 mm×1 mmplates by means of an injection-molding press using an injection-moldingtemperature equal to Tm+20° C. and a mold heated to 100° C. The plateswhich are not entirely crystalline (presence of recrystallization on DSCheating according to ISO 11357-2:2013) are annealed for 2 h under vacuumat Tg+30° C.

-   -   The measurement of the intrinsic or inherent viscosity is        carried out in m-cresol. The method is well known to those        skilled in the art. The standard ISO 307:2007 is followed, but        changing the solvent (use of m-cresol instead of sulfuric acid),        the temperature being 20° C. and the concentration being 0.5% by        weight.    -   The glass transition temperature Tg of the thermoplastic        polymers used is measured using a differential scanning        calorimeter (DSC), after a second heating pass, according to the        standard ISO 11357-2:2013. The heating and cooling rate is 20°        C./min.    -   The melting point Tm and the crystallization temperature Tc are        measured by DSC, after a first heating, according to the        standard ISO 11357-3:2013. The heating and cooling rate is 20°        C./min.    -   The heat of crystallization of said matrix polymer is measured        by differential scanning calorimetry (DSC) according to the        standard ISO 11357-3:2013.    -   The content of amine and acid chain ends is determined by means        of NMR spectrometry.    -   The measurements of permeability to gasolines are determined at        60° C. according to a gravimetric method with CE10:        isooctane/toluene/ethanol=45/45/10 vol % and CE85:        isooctane/toluene/ethanol=7.5/7.5/85 vol %.

The instantaneous permeability is zero during the induction period, thenit gradually increases up to an equilibrium value which corresponds tothe permeability value under continuous operating conditions. Thisvalue, obtained under continuous operating conditions, is considered tobe the permeability of the material.

The results are presented in the following table 1.

TABLE 1 Molecular NH₂ structure/ Inherent Permeability Permeabilitymmol/kg Molar Tm (° C.)/ viscosity CE10 CE85 CO₂H Ref Test typecomposition Tg (° C.) (m-cresol) g•mm/m²•24 h g•mm/m²•24 h mmol/kg 1According to MPMDT/10T 269/131 1.20 0.4 2.4 47 the invention 41/59 38 2Comparative 8MT/9T 265/125 1.25 0.5 3.2 EP1741553 48/52 3 Comparative10I/10T 283/107 1.11 0.4 7 33.3/66.6 4 Comparative 10T/6T/11 269/1141.25 0.8 5 EP1988113 42.5/42.5/15 5 Comparative 10T/6T/11 269/111 1.250.35 6 EP1988113 61/24.5/14.5 6 Comparative 10T/10I/11 265/100 1.15 2.7520 64/20.5/15.5 7 Comparative 11/6T 312/100 1.21 0.65 6.7 35/65 8Comparative 11/6T 273/79  1.05 20 76 50/50 9 Comparative 11/10T 269/85 1.18 3.1 13 33.3/66.6

The compounds of the invention show improved permeability compared withthe comparative examples.

1. A barrier structure chosen from bottles, tanks, containers, pipes,receptacles and films, comprising at least one barrier layer (1)comprising an MPMDT/XT copolyamide wherein: MPMDT is a unit comprisingan amide moiety present in a molar content ranging from 5 to 50%, whereMPMD represents 2-methylpentamethylenediamine (MPMD) and T representsterephthalic acid, XT is a unit comprising a major amide moiety presentin a molar content ranging from 50 to 95%, where X is a C₉ to C₁₈ linearaliphatic diamine and where T is terephthalic acid, said copolyamidehaving a melting point: 250° C.<T_(m)≤300° C. as determined according tothe standard ISO 11357-3 (2013), in the MPMDT and/or XT units,independently of one another, up to 30 mol %, relative to the totalamount of dicarboxylic acids, of the terephthalic acid can be replacedwith other aromatic, aliphatic or cycloaliphatic dicarboxylic acidscomprising 6 to 36 carbon atoms, and in the MPMDT and/or XT units,independently of one another, up to 30 mol % of the MPMD and/or whereappropriate of X, relative to the total amount of diamines, can bereplaced with other diamines comprising from 4 to 36 carbon atoms, andin the copolyamide, no more than 30 mol %, relative to the total amountof monomers, can be formed by lactams or aminocarboxylic acids, and onthe condition that the sum of the monomers which replace theterephthalic acid, the MPMD and X does not exceed a concentration of 30mol %, relative to the total amount of monomers used in the copolyamide,and on the condition that the MPMD is not totally substituted, saidcomposition being devoid of reinforcing fibers.
 2. The barrier structureas claimed in claim 1, wherein said copolyamide has a glass transitiontemperature Tg≥125° C., determined according to the standard ISO11357-2:
 2013. 3. The barrier structure as claimed in claim 1, wherein Xis 1,10-decanediamine.
 4. The barrier structure as claimed in claim 1,wherein none of the monomers of said copolyamide is substituted withanother diamine, another dicarboxylic acid or a lactam.
 5. The barrierstructure as claimed in claim 1, wherein said layer (1) comprises animpact modifier and/or a modifier of core-shell type.
 6. The barrierstructure as claimed in claim 1, wherein said structure consists of asingle layer (1).
 7. The barrier structure as claimed in claim 1,wherein said layer (1) comprises a stabilizer chosen from an organicstabilizer, an inorganic stabilizer, and a mixture thereof.
 8. Thebarrier structure as claimed in claim 1, wherein said layer (1)comprises an antistatic filler chosen from carbon black, graphite,carbon fibers and carbon nanotubes.
 9. The barrier structure as claimedin claim 1, wherein said layer (1) comprises at least one additivechosen from an antioxidant, a heat stabilizer, a UV absorber, a lightstabilizer, a lubricant, a mineral filler, a flame retardant, anucleating agent, a plasticizer and a dye.
 10. The barrier structure asclaimed in claim 1, wherein a second layer (2) is present, the layers(1) and (2) being capable of adhering to one another.
 11. The barrierstructure as claimed in claim 10, wherein said layer (2) comprises atleast one polyamide chosen from an aliphatic polyamide and an aromaticpolyamide.
 12. The barrier structure as claimed in claim 10, whereinsaid aliphatic polyamide results from the polycondensation of at leastone lactam, one aminocarboxylic acid, or of a diamine and of adicarboxylic acid, the diamine being chosen from an aliphatic diamine,an aromatic diamine and a cycloaliphatic diamine and the dicarboxylicacid being chosen from an aliphatic diacid, an aromatic diacid and acycloaliphatic diacid, or a mixture thereof.
 13. The barrier structureas claimed in claim 10, wherein said aliphatic polyamide of the layer(2) is chosen from PA11, PA12, PA1010, PA1012, PA610 and PA612.
 14. Thebarrier structure as claimed in claim 10, wherein another polyamide,different than that of the layer (2) can be present in the layer (2).15. The structure as claimed in claim 10, wherein a plasticizer ispresent in the layer (2).
 16. The barrier structure as claimed in claim10, wherein an impact modifier is present in the layer (2).
 17. Thebarrier structure as claimed in claim 10, wherein said layer (2)comprises a stabilizer chosen from an organic stabilizer, an inorganicstabilizer, and a mixture thereof.
 18. The barrier structure as claimedin claim 10, wherein the layer (1) comprises an organic stabilizer andthe layer (2) comprises an inorganic stabilizer.
 19. The structure asclaimed in claim 10, wherein the layer (1) comprises an inorganicstabilizer, and the layer (2) comprises an organic stabilizer.
 20. Thebarrier structure as claimed in claim 10, wherein said layer (2)comprises an antistatic filler chosen from carbon black, graphite,carbon fibers and carbon nanotubes.
 21. The barrier structure as claimedin claim 10, wherein said layer (2) comprises at least one additivechosen from an antioxidant, a heat stabilizer, a UV absorber, a lightstabilizer, a lubricant, a mineral filler, a flame retardant, anucleating agent, and a dye.
 22. The barrier structure as claimed inclaim 1, wherein the layer (1) is a barrier layer, said fluid beingchosen from a fuel, said fuel being a gasoline, or diesel, an oil, abrake fluid, urea solutions, a glycol-based cooling fluid, a gas, saidbarrier layer (1) being in contact with the fluid.
 23. The barrierstructure as claimed in claim 10, additionally comprising a layer (3),the layer (3) being identical to or different than the layer (1). 24.The barrier structure as claimed in claim 23, wherein the layer (3) isdifferent than the layer (1) and is a tie layer and the structurecomprises, from the outside to the inside, the following layers:(2)//(3)//(1), the layer (1) being in contact with the fluid.
 25. Thebarrier structure as claimed in claim 23, wherein at least one otherlayer (4) is present, the layer (1) being in contact with the fluid. 26.The barrier structure as claimed in claim 25, wherein the layer (4) is alayer of EVOH.
 27. The barrier structure as claimed in claim 25, whereinthe structure comprises, from the outside to the inside, the followinglayers: (2)//(4)//(3)//(1), the layer (1) being in contact with thefluid.
 28. The barrier structure as claimed in claim 25, wherein a tielayer (3′), identical to or different than the tie layer (3), ispresent.
 29. The barrier structure as claimed in claim 28, wherein thestructure comprises, from the outside to the inside, the followinglayers: (2)//(3′)//(4)//(3)//(1), the layer (1) being in contact withthe fluid.
 30. Bottles, tanks, containers, pipes and receptaclesmanufactured with the structure as claimed in claim
 1. 31. Packagingsconsisting of the films manufactured with the structure as claimed inclaim
 1. 32. (canceled)